Mechanization of farm equipment, particularly the type of equipment adapted for connection to tractors having a conventional three-point power lift and utilizing the power takeoff of the tractor has rendered increasingly difficult the hitching or coupling of the implements to the tractor.
The availability of heavier and more powerful tractors has in turn resulted in heavier and more complex implements, to the extent that manual coupling and uncoupling has become almost an impossibility and has become not only extremely unsafe, but time consuming. Further, with the advent of numerous new and improved implements to be towed, even with the voluntary requirement of those implements having coupling frames of certain dimensions for three-point coupling, the provision of a universal coupler has not been forthcoming.
In a recognition of the need for improvement in this field, several coupling arrangements have been developed for use with the three-point lift. One instance, as shown in U.S. Pat. No. 3,306,630 to Weiste, a pair of triangular frames are disclosed, one mounted on the three-point lift and the other on the implement, the frames adapted for a registering engagement for operation, but with no provision for a variance in the implement receiving frame, thus severely limiting the use of the coupling structure to more than one implement.
Anther instance is shown in U.S. Pat. No. 3,432,184 to Tweedy wherein a triangular plate adjustably mounted to the three-point lift is maneuvered into registering relationship with a like-shaped receiving element with inturned flanges on the sloping side edges for releasably lockingly receiving the plate. Again, although ample adjustability is provided for manipulating and locating the plate by hydraulic units attached to the tractor, no adjustability is provided for attaching the receiving element to the implement. Further, this structure prevents use of the tractor pto.
U.S. Pat. No. 3,722,915, while disclosing cooperating guides for guiding upward coupling movement of a coupling member into an opening for registration, is devoid of any teaching or suggestion of providing more versatility to the implement mounting.
It may be seen, therefore, that there is a definite need in this field of coupling a tractor mounted three-point lift to any one of a variety of implements, even where the implement's mounting frame has certain standard dimensions for three point connection, and a need for providing also for full use of the tractor pto in conjunction with the towed implement.